+1 for andreirublev's suggestion to start your trip 'overseas', because pricing for essentially the same trip varies hugely depending on the starting place. Then fly the first third ending at home, a second chunk that you can use to visit North American destinations (Alaska, Caribbean, Central America), and the third to return to your starting point - perhaps ending a year after you began, i.e. next year's 'summer vacation.'

..and for the suggestion to do it in biz.

Planning all that to conform with the rules, and understanding how to avoid extremely high "fuel" surcharges on certain carriers, and extremely high departure fees from certain airports (e.g. London) will keep you busy, but might get you a nicer trip than you had imagined.